In 28 years, Christopher will be 5 times as old as he is right now. How old is he right now?
Explanation: We can use the given information to write down an equation about Christopher's age. Let Christopher's age be $c$ In 28 years, he will be $c + 28$ years old. At that time, he will also be $5 c$ years old. Writing this information as an equation, we get: $c + 28 = 5 c$ Solving for $c$ , we get: $4 c = 28$ $c = 7$.